(Portions of the technical material contained in this section may not be prior art.)
Portable and wireless computer devices, such as PDAs, personal PCs, smart cell phones, etc. are becoming ubiquitous. For convenience, these devices are generically referred to here as PDAs. Many of these devices are equipped with SD slots to accommodate active integrated circuit cards. A common SD function is a memory function, and the cards may be any of a variety of memory cards. For example, one type of SD memory card is a multi-media card, or MMC, implemented using MMC circuits in the PDA. PDA units with WLAN wireless capability have SDIO interface circuits, and use SDIO cards. These provide the PDA with a wireless connection to a WLAN network. The SDIO card in this case carries an RF integrated circuit. The card may also have digital memory circuits to implement other SD functions. Other devices also use SD technology. Many digital cameras are provided with SD slots for SD memory cards. The SD card functions as the image storage medium. In these devices the memory circuit in the card may be very large, to allow many pictures to be stored. Cell phones may also be provided with SDIO capability. These are often referred to as Smartphones. In many of these prior art devices, the PDAs have a single SD function and have dedicated controller units to manage and switch data for the single function.
Recent advances in PDA design and functionality allow more than one function to be accommodated in one PDA device. In these PDAs, a microprocessor host controller is designed to be switched by the user between functions, and to organize and distribute data in response to commands by the user. For example, Intel® PXA250 Microprocessor MMC Controller, originally designed as a single function (MMC) controller, now supports MMC/SD/SDIO functions. See Intel Application Note 278533-001, February 2002, incorporated herein by reference.
A multi-function PDA device may employ a single SD slot, with a separate card for each function. Or it may use cards that contain more than one function. An especially useful multi-function card contains an SDIO function for WLAN communication. See for example U.S. patent application Ser. No. 10/839,901, now U.S. Pat. No. 7,170,754 B2, entitled SDIO MEMORY AND INTERFACE CARD, filed May 6, 2004, and incorporated herein by reference.
In the multi-function PDAs of the prior art, the microprocessors are designed to switch between functions depending on the needs of the user. Thus the multiple functions, while they may present a very large variety for the user, are available only one at a time.